Part Number: LM317AEMP

Manufacturer: Texas Instruments

Description: Linear Voltage Regulators 3-TERMINAL ADJ REG

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Technical Specifications of LM317AEMP

Datasheet  LM317AEMP datasheet
Category Integrated Circuits (ICs)
Family PMIC – Voltage Regulators – Linear
Manufacturer Texas Instruments
Packaging Tape & Reel (TR)
Part Status Active
Regulator Topology Positive Adjustable
Voltage – Output 1.25 V ~ 37 V
Current – Output 1A
Voltage – Dropout (Typical)
Number of Regulators 1
Voltage – Input 4.2 V ~ 37 V
Current – Limit (Min)
Operating Temperature -40°C ~ 125°C
Mounting Type Surface Mount
Package / Case TO-261-4, TO-261AA
Supplier Device Package SOT-223-4

Description of the LM317AEMP

Positive-voltage regulators with three adjustable terminals in the LM317A family can supply currents more significant than 1.5 A throughout an output range that extends from 1.25 V to 37 V and offer an accuracy of 1% in terms of the output voltage. Compared to conventional fixed regulators, the LM317A device is superior in terms of its ability to achieve line and load regulation.

The LM317A provides comprehensive overload protection, including protection against overcurrent and thermal overload and safe-area protection. Even if the adjustment terminal is knocked out of commission, the entire overload protection circuitry will continue to operate normally.

In most situations, capacitors are not required; nevertheless, an input bypass is necessary if the device is positioned more than 6 inches from the input filter capacitors. Instead of an output capacitor, a ceramic component with the appropriate equivalent series resistance could be used. An output capacitor is an optional component that could be used to increase the transient response. By omitting the adjustment terminal, excellent ripple-rejection ratios can be achieved, which is challenging to do with standard 3-terminal regulators due to the inherent design restrictions of those regulators—bypassing the adjustment terminal.

Because the LM317A regulator is floating and only detects input-to-output differential voltage, supplies with several hundred volts can be regulated as long as the maximum input-to-output differential is not exceeded. However, the full input-to-output differential can only be detected when the regulator operates at total capacity. If the maximum input-to-output differential is exceeded, the output will be short-circuited. It is also possible to utilize the LM317A as a precision current regulator if a fixed resistor is connected between the adjustment pin and the output of the circuit.

Features for the LM317A

  • Features of a typical 0.005%/V line regulation 1% tolerance for output voltage
  • Features Adjustable output down to 1.25 V, 1.5-A output current, Up to 40 V of input-output differential
  • The current limit is temperature-dependent.
  • Features output with short-circuit protection
  • Its operational temperature range is from 40 to 125 degrees Celsius.

LM317AEMP Technical Specifications

Accuracy 1 %
Current Rating 1 A
Dropout Voltage 170 mV
Max Input Voltage 40 V
Max Operating Temperature 125 °C
Max Output Current 1 A
Max Output Voltage 37 V
Max Supply Voltage 40 V
Min Input Voltage 4.2 V
Min Operating Temperature -40 °C
Min Output Voltage 1.2 V
Min Supply Voltage 3 V
Number of Channels 1
Number of Outputs 1
Output Current 1 A
Output Type Adjustable
Output Voltage 37 V
Output Voltage Accuracy 1 %
Packaging Cut Tape
Polarity Positive
Power Supply Rejection Ratio or (PSRR) 80 dB
Quiescent Current 60 µA
Reference Voltage 1.262 V
Schedule B 8542390000
Termination SMD/SMT
Tolerance 2 %
Voltage 37 V


Case/Package SOT-223
Mount Surface Mount
Number of Pins 4
Weight 188.014037 mg


      Height             1.8 mm
       Length              6.5 mm
      Thickness               1.6 mm
       Width               3.5 mm


      Lead-Free           Lead-Free
      Radiation Hardening No
       REACH SVHC           No SVHC

Frequently Asked Questions

What is a Linear Voltage Regulator?

Low-dropout linear regulators (LDOs) are linear voltage regulators that employ a transistor in conjunction with a negative-feedback circuit to maintain an output voltage within a narrow range regardless of changes in the input voltage and load current. Linear voltage regulators are also known as low-dropout linear regulators or LDOs. Low-dropout linear regulators are a common alternative name for linear voltage regulators.

How Does a Voltage Regulator Work?

A voltage regulator is a type of circuit that, independent of the load conditions or the voltage being input into the circuit, develops and maintains a constant output voltage.

Devices referred to as voltage regulators, or VRs, are responsible for keeping the voltages produced by a power source within a range compatible with the other electrical components. Although voltage regulators are most commonly used to convert DC power to DC power, specific models may also convert AC power to AC power or DC power to AC power. The most common voltage regulator usage is converting DC power to DC power. This paper will primarily focus on the DC/DC voltage regulator as its topic of discussion.

What are the Basic Parameters for a Voltage Regulator IC?

A few key aspects that need to be considered when utilizing a voltage regulator are the input voltage, output voltage, and output current. With the help of these parameters, a user’s IC can be used to determine whether or not the VR topology in question is compatible.

Additional variables such as quiescent current, switching frequency, thermal resistance, and feedback voltage may be required; however, this will depend on the application.

When maximizing efficiency during light-load or standby phases is a primary concern, the quiescent current is critical. When switching frequency is considered as a parameter, finding smaller system solutions is the outcome of optimizing switching frequency.

The removal of heat from the device and the distribution of that heat throughout the system depend on the device’s thermal resistance. Since all losses, both conductive and dynamic, are dissipated in the package, the integrated circuit’s maximum temperature must be considered if the controller includes an integrated MOSFET.

The feedback voltage is another essential component that must be examined, and it is responsible for determining the minimum output voltage the voltage regulator can manage. It is standard practice to investigate the parameters of the voltage reference. Because of this, the lower output voltage is restricted, and the precision of the lower output voltage impacts the accuracy of the regulation of the higher output voltage.


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